

I only know that you can find it out using a NBT editor of the world/save.
If you suspect that both maps share the same ID and want to check in game if they’re the same ID:
Take one map with you, leave the renamed behind. enter the maps area. Build some blocks and check the map. Repeat until they start to show up on the map (depending on zoom level you only need a single block). Now leave the area of that map and check the renamed map. If it has the same ID, then it will reflect those changes. If not, it has a different ID.
If you have commands on, you might be able to use /data get to access some NBT data from an item in your hotbar, but I’m not sure if the map ID shows there.















Hahahahahahahahahahahahahaha!
As if you’d need to ask that question…